Storage and fuel cells

Page 190 191 Storage and fuel cellsElectrochemical cellsElectrochemical cells are used widely in everyday life as a source of electrical energy.All cells work on the same principle ­ having two redox reactions with different electrode potentials. Forexample, a simple cell can be set up based on zinc and copper,Modern cells and batteriesElectrochemical cells are used as our modernday cells and batteries. Cells can be divided into three maintypes: 1. Non ­ rechargeable cells ­ provide electrical energy until the chemicals have reacted to such an extent that the voltage falls. The cell is then `flat' and is discarded. 2. Rechargeable cells ­ The chemicals in the cell react, providing electrical energy. The cell reaction can be reserved during recharging ­ the chemicals in the cell are regenerated and the call can be used again. 3. Fuel cells ­ the cell reaction uses external supplies of a fuel and an oxidant, which are consumed and needs to be provided continuously. The cell will continue to provide electrical energy so long as there is supply of fuel and an oxidant.Fuel cellsFuel cells have been around for over 150 years. In 1842 Sir William Grove, a Welsh physicist, invented thefirst fuel cell. He mixed hydrogen and oxygen in the presence of an electrolyte and produce electricity andwater. The invention, which later became known as a fuel cell, didn't produce enough electricity to be usefulat the time. Modern fuel cells are based on hydrogen, or hydrogenrich fuels such as methanol, CH3OH.The hydrogenoxygen fuel cellA fuel cell uses energy from the reaction of a fuel with oxygen to create a voltage. × The reactants flow in and products flow out while the electrolyte remains in the cell. × Fuel cells can operate virtually continuously so long as the fuel and oxygen continue to flow into the cell. Fuel cells do not have to be recharged.